1. Field of the Invention
The present invention relates to a high efficiency compact apparatus, available commercially under the trademark combined cyclone and bag filter apparatus, available commercially under the trademark CYBAGFILTER. Particularly the present invention relates to an integral high efficiency compact combined cyclone and bag filter gas-particulate separator apparatus CYBAGFILTER, in which dusts are captured in industrial dust discharging processes such as heavy oil combustion processes, waste incinerating processes, cement manufacturing processes and the like. For this purpose, first, the incoming dust particles are collected based on the centrifugal force principle, and the residual fine dust particles are captured by means of a filter bag disposed above. These two kinds of dust collecting principles are combined into one integral apparatus.
2. Description of the Prior Art
Among dust control equipment, the bag filter is known to control fine dust particles of 0.01 .mu.m by more than 95%.
However, whereas it has high performance, it also has several disadvantages. That is, as the dust capturing operation proceeds, the dust cake on the filter bag surface becomes thick, and therefore, the pressure drop becomes high, with the result that a normal operation becomes impossible.
Therefore, cleaning operations have to be carried out periodically, that is, the dust cake accumulated on the filter bag surface has to be discharged.
The cleaning operation is carried out in such a manner that mechanical force or a strong dynamic energy is applied to remove the accumulated dust cake from the surface of filter bag. However, if the dust concentration at the inlet is high, or if the filtration velocity(air-to-cloth ratio) is high, or if the dust cake is intractable to the cleaning operation, in order to efficiency conduct a bag filter operation, the cleaning operation has to be carried out more frequently, or a large amount of high pressure jet of air has to be injected into the top of the filter bag.
When such a strong cleaning operation is carried out, the pore size of the filter bag becomes large. Then dust particles pass through enlarged pores of the filter bag, with the result that the dust collection efficiency is lowered. Further, due to the short interval of cleaning operations, erosions occur between the filter bag and the bag cage, with the result that the filter bag is worn out and damaged, thereby shortening the filter bag life.
Furthermore, if the filtration velocity is designed to be fast, although the size of the bag filter becomes small, the pressure drop is drastically increased. Therefore, a low filtration velocity has to be applied inevitably.
If the dust loading is high on the bag filters, the pressure drop is drastically increased. Therefore, in order to reduce the dust loading, a cyclone is installed upstream of the bag filter, so that the coarse dust particles can be collected first, thereby reducing the dust loading on the bag filters.
However, upstream cyclone is low in the collection efficiency, and, due to the carelessness in its operation and maintenance, the reality is that the cyclone is not properly utilized.
Furthermore, in order to efficiently collect dusts discharged from the industrial process, pre-dust collectors and final dust collectors (bag filters, etc) have to be installed.
Accordingly, in the domestic industries, the installation costs are high due to installation of the two units of dust control equipment. Further, the installation area has to be large, and more manpower is required to operate the two units of the dust control equipment. This has been the reality so far.
FIG. 5 illustrates the conventional industrial dust control equipment. In this equipment, a cyclone and a bag filter are separately installed.
The design standard for the cyclone separators is such that the standard model is adopted. That is, it is the one that is proposed by Lapple, Swift or Stairmand. In this design, the height and the width of the inlet, and the diameter and height of the outlet, and the overall height were decided based on the diameter of the main body of the cyclone separators.
In the conventional cyclone separators, the dust-laden gas flow is formed from above in a tangential direction. Thus a vortex is formed to descend along the wall (forming a first vortex). Then the vortex is reversed at a lower tip of a conical vessel to then ascend (forming a second vortex).
Reference code A in FIG. 5 indicates a dust-laden gas inlet, B indicates a cyclone separator, C indicates a rotary valve, D indicates a bag filter, E indicates a manometer, F indicates a diaphragm valve, G indicates a timer, H indicates a compressed air header, and I indicates a clean air outlet.
Therefore, a combined type dust control equipment is in demand in which a single unit serves the prior dust collecting functions of the two units of the dust control equipment, and in which the required installation area is small, and the installation cost is low.
The worldwide trend of the development of the dust control equipment will be described below.
That is, there is a limit in the conventional double-unit dust control equipment, and therefore, a compact hybrid bag filter is under development in which the conventional two units are merged together.
Examples of the apparatus in which the principle of the cyclone and the principle of the bag filter are merged are Simartek's Vetyton Jet Air Filter of Denmark, Multizyklone's Turbofilter of Germany, and Krantz-Tkt's AS filter of Germany.
In the Simartek's Vetyton Jet Air Filter of Denmark, a dust-laden gas flow which is incoming from above spins and descends, so that coarse dust particles are captured, and fine dust particles are transferred to a filter bag disposed above, so as to be collected. In this apparatus, the structure is dual, and the installation cost is high.
In the Multizyklone's Turbofilter of Germany, a filter bag is combined to a multiclone. In an incoming flow the dust particles in the dust-laden gas are first collected by the multiclone, and the uncollected dust particles at the multiclone are further collected by the filter bag. In this apparatus also, the structure is complicated, and efficient operation is impossible. Further, the installation cost is high, and the filtering operation and the cleaning operation have to be separately carried out.
In the Krantz-Tkt's AS filter of Germany, coarse dust particles are removed by a cyclone disposed below, and fine dust particles are filtered by a filter bag disposed above. In this apparatus, the shape of the filter bag is rectangular, and a cleaning device is installed right above. Therefore, the replacement of the filter bag is difficult. Further, a clean air sucking device (i.e., a fan) is installed above, and therefore, the construction of large scale equipment is impossible.